Magnetron



1952 R. B. NELSON 2,607,898

MAGNETRON ile Oct- 5, 1946 :5 Sheets-Sheet 1 Inventor-z Qichahd BNelson,

H i Attdhney R- B. NELSON Aug. 19, 1952 MAGNETRON 3 Sheets-Sheet 2 Filed 001;. 3. 1946 Fgs.

m s hum M t nB e v f ,mmw b 5 HS Attorney.

Patented Aug. 19, 1952 MAGNETRON Richard B. Nelson, Schenectady, N. Y., assignor to General Electric Co New York mpany, a corporation of Application October 3, 1946, Serial No. 700,939 21 Claims. (01. 250-36) This invention relates to electron discharge devices and oscillating circuits of the magnetron type and has for its object the provision of an improved tube construction having numerous advantages such as simplicity for manufacturing purposes, readily accessible and conveniently detachable external tuning means operable throughout a wide range of frequencies and improved relatively high power output, efficiency and operating life resulting from such features as an improved fluid cooling means, improved dielectric loss characteristics in the seals and minimized destructive bombardment of the envelope and seals by electrons escaping from the electronically active regions of the device- It is a further object of the invention to provide an improved oscillating circuit in which the improved tube finds useful application.

The features of the invention desired to be protected are pointed out in the appended claims. The invention itself, together with its further objects and advantages, will best be understood from the following description taken in connection with the accompanying drawings in which Fig. 1 represents a cross sectional view of an illustrative magnetron discharge device embodying the invention; Fig. 2 represents a cross sectional view taken in the direction of the indicated arrows along a plane through the line 22 of Fig. 1 and vertical to'the drawing; Figs. 3 and 4 represent similar cross sectional views of an alternative embodiment of the invention in a magnetron discharge device; Fig. 5 illustrates an oscillator employing discharge devices of. the type shown in Figs. 1-4 and certain other features of the invention; while Figures 6 and '7 represent alternative constructions for oscillators or similar devices of the type exemplified in Figure 5. Inthe drawings like numerals have been used to designate like parts throughout.

. Referring now to Figs. 1 and 2 it will be seen that the device comprises generally an hermetically sealed envelope l, preferably of thin steel tubing, within which there are mounted a pair of magnetron anodes 2 and 3, a thermionic cathode 4 and a pair of magnetic pole pieces 5 and 6. The anodes 2 and 3 are provided with juxtaposed cylindrical faces defining a generally cylindrical chamber about and concentric with the. axis of cathode 4 and the magnetic pole pieces 5 and 6 are so arranged as to establish, when suitably energized, a magnetic field parallel with the axis of the cathode within the cylindrical space defined by the anode faces. As will'be well understood by'those skilled in the art to which the invention pertains, the 1m:-

position of a relatively high positive potential on the anode with respect to the cathode will,.

in the presence of a sulficient magnetic field, establish a rotating electron space charge in the region defined by the anode faces and that such,

space charge. will induce high frequency oscilla-.

tions in the magnetron and its attendant circuits.

The magnetic pole pieces 5 and 6 may be formed of any suitable magnetic material such as non-permanently magnetic soft iron or, if permanent magnets are desired, they may be of any suitable permanently magnetizable material such as the class of alloys of aluminum, nickel and cobalt generally known as Alnico. Alloys of this type are described for example, in Tokuschichi Mishima Patents 2,027,994 to 2,028,000, inclusive, and are further described in W. E. Ruder Patents 1,947,274 and 1,968,569. If non-permanent magnetic pole pieces are desired, any suitable means for magnetizing them maybe provided externally of the envelope such as a pair of solenoids (not shown) juxtaposed to the envelope surface. In that event, the thickness of the-enevelope I may be minimized in order to increase its magnetic reluctance thereby minimizing its shuntingeffect which tends to reduce the magnetic flux passing through the pole pieces. If, on the other hand, the pole pieces are permanent magnets thus providing an internal rather than external magnetizing force, the envelope will advantageously tend to minimize the magnetic reluctance of the useful magnetic circuit and consequently minimize the value of the required force. In that event its thickness may be maximized to the extent consistent with other design factors.

The pole pieces 5 and 6 may be welded or brazed to the envelope or fastened thereto by any other suitable means. Alternatively, they may be supported from the rings 1 and 8 hereinafter to be described or affixed by means of a bolt 9 as in the case of pole piece 6. Moreover, they are preferably shaped to conform to the contour of the envelope in order to minimize air gapsand thereby to minimize the magnetizing force necessary to establish the desired magnetic field. c

For the purpose of providing forced cooling of the anodes 2 and 3 and adjacent structures when the discharge device is operated at a high-power output level, there may be provided a set of fluid coolant channels such as U-shaped tubes In and II of copper tubing which are built into externally accessible recesses l2 and [3, respectively, in the anode structure. The outer connections it may be left bare of coating and operated as an uncoated thermionic filament. The coil Mds.

supported. on a rod l5 having end shields l6 and I! which serve to enclose further the-cylindrical space charge chamber defined by the opposing anode surfaces. H is conductively connected to. the shield l1- and therethrough to rod l5, core l8, and externally accessible terminal l9, while the other is like wise connected through an intermediate connection to tube2l leading to an externally acces sible terminal 22. The entire cathode structure may be supported by-the concentric tubular con struction 23 shown as projecting throughthe envelope l and into a cylindrical cavity: in the pole piece 5% The'construction 23 is comprised of a sectionalized outer cylinder 24', the inner metallic tube 2| and the central metal core or rod l8 which forms-a conductive support for the cathode t". Outer-cylinder comprises metallic cylinder 25 a-ffixed to the pole piece 5 and envelope-l as by brazing, cylindrical collar z t-welded by'means of an end flange 2 to a similar flange 28 'on cylinder 25, cylindrical glass seal 29,- cylinder 30', cylinder3l having an end flange32 brazed to a' similar end flange 33- on cylinder 30 with annular shaped". terminal 22 in between the two, cylindrical; glass cylinder itand pup-shaped collar 35; The cylinder-2t constitutes an hermetically sealed structure by virtue of the brazing at the metallic joints and. suitable glass to metal seals atthe glass to metal joints; Tube 2 l 'is-supported .by brazing to theijuncture of cylinders 30 andjSl and terminal'22while core I8 is supported bybrazing to collar 35; a metallic washer 36- furnishing additional support; Terminal lfiisprovided on the end of the collar 35 for affording a suitable. ,and convenient external contact for the cathod'elead.

As. will be understood by those skilled in, the

art,.tliere is,,in devices of this nature, a tendency for electrons to escape from the space charge rotating in the cylindrical region between the anodes .and.to migrate to. other parts of the tube under. the influence of. the various electric and magnetic fields. In particular, the electric field due-to the high frequency voltage on the anodes, can act in conjunction with the magnetic field toiproduceelectron pathsclosely following the anode surfaces. These escaping electronsunless stopped will continue along the anode. surfaces untilthey strike-the glass seals, hereinafter to be described, and heat them to the. melting point, whereupon they destroy the device. This. phenomenon is not only destructive of the discharge device; asv a whole but generally impairsrits efficiency.

To prevent, or at least minimize this action, there may be provided a pair of annular suppressor: disks; 3'! and 38 extending around. the periphery of, they envelope: Such disks may, for example, be formed of. a. suitableiconductive ma.- terialpreferably one which isnonemagnetic and which does not give "rise to substantial-secondary emission of electrons when'bombarded' by elec- As shown, one end of the coil trons. I have found disks of molybdenum satisfactory for the purpose. The disks may be mounted on insulating bushings 39- and 4B of quartz or like material. The bushings may in turn be mounted by means of nut and bolt structures H on the metallic rings 1 extending around theperiphery of the envelope l and being welded or otherwise rigidly attached thereto. .Upon be ing struck by escaped electrons the disks 3'! and 38 will charge negatively until they repel subsequent escaped electrons and prevent them from reaching the glass seals. The effectiveness of these suppressor disks 3'1 and 38 has been found tozbe most satisfactory in that in all the discharge devices: made thus far there have been no seal failures which could be attributed to electronic. bombardments.

In order to provide a sealing structure in which the electrical field stresses created in the dielectric materials such as glass, by the oscillating field'sare minimized, the-connections to: the" respective anodes are preferably:broug-ht out oppo-- site ends of the envelopewhere they may be conveniently connectedtoconcentric line con structions'hereinafter to bed'escribed. With such anarrangement the seal structureshown becomes, possible; It comprises the vitreous seal members- 62 of; glass or-like dielectric material bonded by suitablaglassto metal sealing methods to metallic'collars43' and' id andcyl-indrical members and 45; supporting the anodes 2 and 3, respectively. The cylinders'fl and 6'6 will, of course, be brazed'or otherwise; hermetically and rig-idly attached to cylindrical recesses in therespective anodes. The entire. structures comprising" the collars 43: and', the. members 4-2,- the'cylinders 45 and 4B, and the respective anodes may be fabricated. as units' afterwhich the units are positioned within the envelopewith' the cylindricalgsurfaces of thecollars. 43' and M supporting the. entire structures and positioning-itin alignmentwiththe axisof the envelope; Within the. concavity formed by the seal construction the U-shapedi copper tubes [6' and It may" be supported'by any suitable. means such as'by'brazing to. the. anodes. I They are shownasbeing fitted into. cylindrical recessesv in the; anodes to facilitate supports.

The foregoing seal construction advantageously permits improved dissipation of heat developed. in the dielectric seal members by. reason of. the fact that the seals are made. as largea-s the envelope diameter and'contact the heatdissipating metal surface of envelope l over-a maxi mum area. Moreover, the heatenergy'developed' withinthe. dielectric as well as the electric fields centrated in a narrow region betweenthe'two;

parallel wires. thereby intensifying the destructive-effects onlimited portions of the dielectric. Moreover, it will be noted that theinverted dome shape of the rseal permits sliding tuning mam-.- bersto approach relatively close to the anode of the device'thereby permitting effective tuning to ,higherf'requencyand throughout a greater range of frequencies in the manner hereinaftersmore fully't'o be described. 'For additional cooling, air may be blown-through the center'of the concentric'conductors to cool the seals, the outwardly concave surfaceof: the glass. advantagously "directing-"the outward' flow of air and insuring more 'eiTec'ti've cooling' contact between the air andglass'than would be the. case'lwith an outwardly convexsurface; iThat is'Z to say, the. cooling air naturally'follows the concave surface close contact therewith, whereas with a conv'ex 'surface'it' woulcl tend to be deflected away thereby tendi'ng'to make only point/contact.

'For'the' purpose'of permitting visual observa tion of the'cathod'e where it may be desirable to taketemp'erature measurements thereof by optical means, there --may be provided a window 4T-sealed to a metallic cylinder 48 by suitable glass 'to metal sealing methods. Cylinder 48 may be welded't'o a-cylinder 49 by means of annular flanges :50 and 5| ontherespective cyl-. inders, the cylinder 49 being hermetically sealed througha 'suitable hole in envelope l. *Alternamely, cylinder 48 'may be hermetically sealed through such hole.

The described device may be hermetically sealed at' all-points and may be evacuated in known manner through 'a cylindrical tube 52 welded hermetically toa hollow threadedstud 53 likewise hermetically sealed. to envelope l. Sealing fafter evacuation may 'be completed by glass bead54sealedacross'tub'e 52. A protective cap:-55;' threadedly engaging stud 53 may be provi'ded to protect the structure from breakage. In-Fi'gs. 3 and-4' therezis shown another embodiment' of the invention in a magnetron type discharge device employing I also the :Jprinciples of' 'construction disclosed and. broadly "claimed in. a cop'ending application. Ser.? No.1; 601,126 of Donald "A. Wilbur', filed June 23; 1945, for .zElectric Discharge Devices, and assigned 'to the "same a'ssigne'e as theipresent application. "The char-' acteristic'featurelies in the'provisionof addi tional andelctric'ally' neutral electrodes defining with the anodes, such as the anodes 2 and 3 of Figs/1 and 2, a "cylindrical chamber within which the rotating-electron'space charge rotates. Except for the provision of such additional electrodes 56"an'd 51.in'Figs.3 and 4 and the optional omissi'on'ofth'e annularirings I and 8 and annular'shieldstland '38 of Fig. 1,. the construc-' tion shown in Figs: 3 and lis identical with that shownin Figs. 1 and-2. Thereforefin the interestcf clarity, repetitionof. the description'of thecommon features and enumeration of those features on the drawing has-been omitted in Figs. 3'and4.. R;,eferring now to' Figs; 3 and '4,'it willbe noted that an additional-pair of. electrodes 56 and 51 has been provided and that these electrodes define with the .anodes 2 and-3 (corresponding to those of Figs; .1 and2)-a cylindrical chamber in whichthe electron space charge may rotate coaxially with .the cathode 4. ,Anodes' 2 and 3 are; of course, modifieddn shape-from-that shown in'Figs. land 2 to permit the insertion of the electrodes 5'6-and51. The electrodes 56 and 51 may be conformed to the shapeofwtheeenvelope I and affixed thereto-asby brazing, welding or any other suitable means. Preferably the electrode 51 will be provided with a channel 58 providing a path for the outflow of gases during the evacuation process, while the electrode 56 may be provided with a channel 59 aligned-with the window 41 to permit visual observation of the cathode, .as. hereinbefore de scribed. The, electrodes"56"and 51 will, of course, be-electricafly common with the envelope I and will-be connected thereto at points whichwillassume' electrically' neutral potentials 1 with respect to high frequency voltages on the envelope is e. points having zero high frequency voltage such asnodal points of the standing wave set up in the-envelope and its attendant 'resonant'circuit during oscilla tion. H

With the electrode configuration shown in Figs; 3 and 4 it will be found that for a given frequency of oscillation (which is, ofcourse," always determined primarily by the inductive 'and capacitative characteristics of the ems-namesonant circuit such" as the resonant transmission lines hereinafter to" be described); the angular velocity of the rotating space charge configuration will be only'half of that for the construction of Figs. 1 and 2. According to. the prevailing view. of the manner of operation of 'magnetrons of the general type involved, this result'r-arises from the fact that the.rotati0'n of the" space charge tends to synchronize with thelhighfrequency electromagnetic 'fieldsestablished in the vicinity of, thegaps between the electrodes by the oscillations in the external resonant circuit. With the greater number of gaps, a smalleri an.- gular .velocity is requiredto maintain synchro nization since the space charge passes across-the face of each electrode or anode in a half cycle ofthe frequency oscillation. In accordance with th principles set forth in the aforesaid Wilbur application serial Number 601,126 the; angular velocity can be made still lower by decreasing the angular-extent ofgthefaces of the anodes 2 and 3 and correspondingly increasing the angular extent of the-faces. of the electrodes .56 and-"5T. Moreovenxthe effects desired can, also be, accomplished with but a single neutral electrodesnch as the electrode 51.; In thelattercase the faces of the anodes zand -3 willbe extended angularly v to include the sectors-shown in cupied by electrode 56.

the Fig. ,3 as ;oc.-

art to. which the invention pertains,- the advantagesof constructions such as areexemplifiedin the Figs; 3 and 4 will include a reduction of .de; structivev and power wasteful effects of cathode back heating, simplified magnetic energizing means and. the possibility of constructions capable of attaining higher oscillation frequencies. Thefirst two of these advantages may beattributedprimarily to the fact that the val ues of the magnetic and, unidirectional electric ,fields required to energize the device may be reduced in proportion tothelowering of the angular velocity of-the space charge configuration; Ener-v gizingfields ofsuch lesser value may-be estab: lished withsimpler apparatus andwill;,because of their. lowerya'luetend to reduce electronwvee locities which effect destructive back-heating of the cathode. Conversely, constructions capable of attaining higher oscillation frequencies become possible because the correspondingly higher an-..

gular' velocities of the space charge maybe attained' before thevaluesof the necessary-mag.- netic and unidirectional electric energizin'gfields Aswill be understood bythose skilled in the 7 spends. generally tea cr ss; s ctionxtalsenza one th.e.; nes;,55 of; Fig. .1 na p ane perp dicular to-the'drawin except, of course,.for the attached coaxial output lines presently'to' bedescribed. In view of this-correspondence, like numeralshave been :used to designate corresponding parts. For example, the. anodes. are. designated .2 and 13; the magnetic pole pieces 5 and 6, the cathode. 4, and the collars 43 and 44, as in Figs. 1 and 2.

Referringnow to Fig. 5, it will be seen that there have. been provided on 'both ends of the electrical-discharge device coaxial transmission linescomprising respectively inner conductors fiflandrfij and outer conductors 62 and'63; Both the' inner "and the "outer. conductors are provided with a:- peripherally. extending seriesof spring fingers.- 164 and 6.5 respectively. Fingers 65' resiliently-engage the inner surface of the respec tiveccollars 43 and 34. in order to provide good electrical contact between .the outer conductors 62"iandi:63' 'and the metallic envelope l.- The spring fingers 64' resiliently engage the inner-surfaces-of cylinders 45 and to form good-electrical" contact with the cylinders and cruise querrtly with anodes! and 3. In eiiectthecon-v ductors Hand '63 therefore form conductive extensions of the envelope I, thereby forming with envelope |,.the' outer conductor of a continuous concentric line. Inner conductors 66 and 6! etfectivelyiorm in a similar manner a continuous inner-conductor for the line broken only byrthe anode gap. Asindicated in Figs. 1 and 2; the-collars 43 and 44- maybe shaped to receive conveniently the spring fingers 65.' It will'be observed that these constructions provide-convenient means whereby 'detachable'external con; nections may be made betweenthe discharge device andsuitable concentric output lines to t be employed therewith. Such connections may be rapidly and conveniently detachedshould; it be desiredto replace the sealed device or to provide a differ'ent external circuit therefor.

For the purpose of tuning the device, for ex ample, if it is employed'as arroscillator, suitable shorting means electrically terminating a the transmission'lines on either side may hegemployed. In the case of the line comprising -the conductors fifland 62'the short is shownascomprising-an annular-shaped tuning," member 66 slidably mounted on the inner conductor 60gand soarranged as to engage both the inner and the outer-conductor with good electrical contact. As is understood by those skilled in the art, the position of'such tuning members longitudinally of the line determines the frequency of oscillation and'the'highest frequency which cange generatedbytho arrangement is determinedby how close'the members can bebrought to the anodes of -'the device. As already indicated hereinbeforeg'the-d ome-shaped seals of the device'areinverted fr'om their customary position so that the-convex side is presented to the evacuated chamber. This feature allows the sliding shorts to -approach very closely to the anodes and that distanceis further shortened by appropriately shaping the' shorts to fit within the concave surface -of the seals. A similar vshort may be provided in the line comprising conductors. SI and 63.

For the purpose of providing a convenient means of deriving power from the oscillating anode tank circuit, i. e. that portion of the transmission lines between the shorts. and the anode, the short on one side of the device may be made purposely leaky so that a portion of the tank circuit power will be transmitted through itinstead-zot reflected. The transmitted portion will 8 therefore :flow; beyond:- the shorts tc;r-an.sex;tended portion; 10f ztheitransmissiont 11.118." "and? thus 1 to any. iurthermtilization.icircints (not shown);. Such a leaky short .isshowminternalb' of==-th transmission: dine; comprising the :co d and '63:. It .representseleQtrmall ductance-acrossthe.transmission:l ne,.-yariebleiby sliding-:its-two parts;;relative-;toreach other: and thus. changing rithei'length of theyshunt. :It-will be seen that iticem riseis. amannular plunge 61 mounted upon a .cylinderyfifiolosely fittingand sliding'on. the inner conductor -,6l,'whcreby the plunger I 6:1 may be :slidably 'positioned along the length thereof.- The; positioning; may: be. accomplished by means-etamanually:opera le stud 69 which is guided:by.;a;.ilongitl1dinal: 1t 1.0 theoutericonductor 63.. Asdndicatedithd plun er 61 of: somewhatdesser diameter than .the'i er diameter. of the-outer conductor 6.3: and-that therefore aicertain amount: of oscillatory-energy may flow-pastthesame' to the external portions of .the transmission line: Additionally; it may-r116 provided with: '1 spring fingers 1 I to insure-good electrical contact with conductors-Bil. lm rder to vary the amount of leakagegofgenergy past the plunger .61. anauxiliary sliding member 12; may be provided and mounted on. azcy'linder 1.3 which slidablyengages the outerconductortfi bymeans of'spring-fingers-14i A; further-set oi spri fingers T5.=within-the-. cylinder 13;permitsit to makefir'melectrical; contact @with the. rind 5. 9.0. ductively attached-to the-plunger Ki'l whilerin relative motion with :re'spect .theretm; Motiomof the member '12 :with irespectst'o the: plunger- 61 is accomplished by meansof the. manually operable stud =1?! guided by-rthe longitudinal *slot 16 in:'a'tmanneri'similar'to.thatxof stud 69.:

r The foregoing structure'will be. 'fOllIld'ItOTPIO: vide a practical. means iofisimnltaneously'. tuning the transmission :line; comprising: .z'ronductors 6.! and 63: so thatiti may be tuned with the transmission'line comprising conductors 60 and BZ; and forsimultaneously varying the: amount of energy leaking past-the short. as desired. It w'ilbbe "understood: that suitable' cooling means such a ithose :hereinbefore;discussed may be usedior-"the purpose of cooling the anodes 2 and '37 and the. seals adjacent thereto. Such meansyareindicated only schematically in Fig. 5 as'the tubing 18 and'lfi passing through the inner conductors-Gil and 6! respectively tothe vicinity-of :theuanodes. The structure at-the anodes.- will "be. that shown in Figs.- 1 and 3'. Additionally, air" may be-forced through the inner conductor by any suitable means (not shown) inorder that it maypass into the space between the inner and outer conductors, thereby flowing past theglass seals in=its path of escape to 'slot '10 orany'other open portions of the lines." a

It will also be understood 'that'oscillations may be generated the arrangement of'Fig. 5 'whenever it is energized'by a suitable unidirectional electric potential impo'sed between i the anodes 2 and 3 and cathode 4 in the presence of a-suitable magnetic field directed perpendicular to=the electric iield'i; e. a magnetic field directed gerrerally parallel to the axis of cathode 4. The electricfield may be provided'by any suitable means such as battery 81- having its negative terminal attached to the cathode 4 and its positive term'inal'to the envelope 1 which is conductively connected to; anodes 2 and; 3' through the tuning means. The magnetic field represented by the arrow H maybe provided by any suitable means (not shown) such as an 'electromagnet 9. positioned adjacent the envelope and pole pieces and 6.

Fig. 6 illustrates schematically an alternative arrangement wherein the outer conductors in Fig. 5 have been omitted and the inner conductors now designated 8| and 82 are bent at right angles to the axis of the devicein order that they may be brought out as parallel lecher wire transmission lines. The latter lines will form a standing wave resonant circuit for the device operating as an oscillator in a manner well known in the art. For the purpose of tuning a shorting rod or plate 83 may be employed across the lines in a manner well known in the art.

In Fig. 7 there is illustrated an oscillator which is substantially identical with that of Fig. 5 except for-tuning means and the means -for extracting power for the resonant tank circuit. Except for the latter means the corresponding elements have been designated by like numerals. V

In order to insure that the tank circuit connection to both sides of the magnetron device are tuned to the same frequency at all points in. the range of the oscillator, it is desirable that the tuning shorts in the respective transmission lines formed by conductors 60 and 62 in the one case and BI and 63 in the other are symmetrically positioned. That is to say that the tuning shorts should be generally equally distant from the center of the magnetron device at all times. In the Fig. 7 there is shown a pair of tuning shorts 84 and 85 which tune the respective transmission line in the manner well known in the artf The tuning shorts are each mountedon an annular collar 86 and 81 slidably engaging the outer conductors of their respective'lines. The tuning shorts may be connected to. the collars 86 and 81 by means of an extension. extending through longitudinal slots 88 and 89 in outer conductors 62 and 63 respectively. The collars 8'I and 88 may be driven longitudinally of the transmission line by means of threaded members .90 and BI which engage the threads of a crank rod 92' and which are connected to the collars 85 and 86 by means of suitable studs 93, and 94.

The rod 92 is provided on either end with reverse.

threads in order that rotation of the rod will cause simultaneous movement of the shorts 84 andr85 away from the magnetron device, if roone of the tank circuitsithere may be provided a co-axial output line having an inner conductor 98 and an outer conductor 99 both of which'are connected to any suitable energy utilization circuit (not shown). The outer conductor 99 may be connected to the outer'conductor- 03' by. means of acollarl 00 slidably mounted on the conductor electrical contact therewith; gonduc; L

tor '98 may makeisliding, contact withithe "inner conductor; 6| by means oftheyextens'ion IOZite'r-i The inner conductor 98may enter the outer condoctor 63 through the longitudinallsloti89L} vI .1 It will be understood that the amount of poweri extracted by the line 98 H, irgmthe oscillatozi.

will be dependent on the position of the collars I00and I03, alongthe transmission line and for the purpose. of varying that amount of power the line 9899 maybe positioned bysliding along the line 6I,-63. To that'end, collar I00 may be adjustably positioned with respect to the tuning short 85 by means. of a. threaded memb,er; l05 which engages the collar I00 by meansv of a stud I06 and which is positioned with the respect to member 9I by means of the threadedsleeve I01. The sleeve I01 will be slidably mounted on a rod I08 in such a manner that it may slide freely in a longitudinal direction and yet be turned by rotary motion rod I08. To this end the cross.- section of rod I08 and the internal cross-section of I 01 may be rectangular. It will be noted that the sleeve I 01 is fixed to the member 9| in order that the tunin shortand the collar I00 will move in unison when ever the tuning is adjusted. by means of the crank 95. The crank I09 will serve to rotate the sleeve I0'I whenever it is desired to change the relative position between the output line 98-99 and the tuning short. It. will be understood that the rod I08 may be similarly affixed to the standard 91 and to a fixed standard IIO. It may be. journalled therein by means of a pin I I I.

As an illustration of the performance which may be obtained from oscillators embodying the aforedescribed invention, it is noted that in one suchconstruction I have been able to provide an oscillator which will perform in a highly satisfactory. manner over a frequency range varying from approximately 85 megacycles to 360 megacycles, i. e., a range of 4 to 1 in frequency. Generally the efiiciencyof arrangement was about 50% at all frequencies- The maximum power output varied from one kilowatt at the ends of this frequency range to about 3 kilowatts at its center. J

While I have shown and described a particular embodiment of my invention, it will be obvious to those skilled in the art that various changes and modifications may, be made without departing from my invention in its broader aspects, and I, therefore, aim in the appended claimsto cover all such changes and modifications as fall within the true spirit and scope of my invention.

-What I claim as'new and desire to secure-by Letters Patent of the United States is :J

1. An electron discharge device of the magnetron type comprising an hermetically sealed envelope includin a substantially cylindrical metallic portion and seal members of insulatingjmaterial herer'ntically sealing each end of said portionga pair of anodes within said portion having juxtaposed faces defininga space charge chamberir'withinsaid envelope, each of 'said anodes having an externally accessible conductive connection passing through one of said seal members,-ia cathode positioned within the chamberdefined fby said anodes, and means within said envelope supporting and positioning said cathode, said 's'ealmembers' 'having a generally? convex portion extending inwardly of the ends'of said envelope. w

2; An electron dischargedevice of the magnetrohtypelcoinprising an hermetically sealed en'-" vielo'pe. l including 1 a -'substantially cylindrical metallic portion and seal members of insulating material hermetically sealing each end of'said" portion, a-jpair o'f anodes-within said portion having juxtaposed faces. defining a space charge chamber within said envelope,- ea'ch ofsaid 'anodes'being supported' from one ofsaid seal tending radially of said envelope, a pair ofsaid electrodes being supportedeach from one of said seal members in insulated relation to said portion and each having an externally accessible conductive connection passing through one of said seal members, at least one other of said electrodes being conductively supported from said portion,

a cathode positioned within the chamber defined by said anodes, and means within said envelope for supporting and positioning said cathode,

11. An electron discharge device of the magnetron type comprising an hermetically sealed envelope including a substantially cylindrical metallic portion and seal members of insulating material hermetically sealing each end of said portion, said seal members having a generally convex portion extending inwardly of the ends of said envelope,

a plurality of electrodes centrally within said portion having juxtaposed faces defining a generally cylindrical space charge chamber having an axis extending radially of said envelope, a pair of said electrodes being supported each from one of said seal members in insulated relation. to said portion and each having an externally accessible conductive connection passing through one of said seal members, another of said electrodes being conductively supported from said portion at a longitudinal midpoint thereof, a cathode positioned within the chamber defined by said anodes, and means within said envelope for supporting and positioning said cathode. 7 i

12. An electron discharge device of the magne-v tron type comprising, an hermetically sealed envelope including a substantially cylindrical metallic portion and seal members of insulating ma-- terial hermetically sealing each end of said portion, said seal members having a generally convex portion extending inwardly ofithe ends of said envelope, a plurality, of anodes within said portion having juxtaposed faces defining aspace: charge chamber within said envelope, eachiof.

one pair of said anodes having an externally accessible conductive connection passing through one of said seal members-each of another pair, of said electrodes being conductivelyconnected to said portion, a cathode. positioned within the chamber defined by said anodes, and means within said: envelope for supporting and positioning said cathode. i,

13. An electron discharge device of the magnetron typecomprising, an hermetically sealed envelope including a substantially cylindrical metallic portion and seal members of insulat-v ing material hermetically sealing each end of said portion, said seal members having a generally convex portion extending inwardly of the ends of said envelope, a plurality of anodes within said portion having juxtaposed faces defining a space charge chamber'within said envelope, each of one pair of said anodes having an externally accessible conductive connection passing through one of said seal members, each of another pair of said electrodesbeing conductively connected to a longitudinal midpoint of said portion, a cathode positioned within the chamber' defined by said anodesand means within said envelope for supporting and positioning said cathode. I 14. An electron discharge device of the'magn'etron type comprising, an hermetically sealed envelope including a substantially cylindrical metallic portion andseal members of insulating material hermetically "sealing" each end of said portion, said seal members havingagener-' ally convex, portion extending inwardly of the 14 ends of said envelope, a plurality of anodes v within said portion having juxtaposed faces defining a space charge chamber within saidenvelope, each of one pair of said anodes havingan externally accessible conductive connection pass-v ing through one of said seal members, another ofsaid electrodes being conductively connectedio 1 1 said portion, a cathode positioned within the chamber defined by said anodes, means within said envelope for supporting and positioning said cathode and means within said envelope for establishing a magnetic field within said space charge chamber.

15. An electron discharge device of the magne tron type comprising, an hermetically sealed envelope including a substantially cylindrical metallic portion and seal members of insulating, materialhermetically sealing each end of said portion, said seal membershaving a gener ally convex .portion extending inwardly of the ends of said envelope, a plurality of anodes centrally within said portion having juxtaposed. faces defining a space charge chamber within said envelope, each of one pair of said anodes having an externally accessible conductive con-i nection passing through one of said seal members, another of said electrodes being conductive- 1y connected to a longitudinal midpoint of saidportion, a cathode positioned within the chamber defined by said anodes, means within said envelope for supporting and positioning said cathode,

and magnetic means within said envelope adjacent said anodes for establishing a magnetic field within said space charge chamber. I i

16. A generator of high frequency oscillations comprising in combination an electron discharge device of the magnetron type including an hermetically sealed envelope having a substantially cylindrical metallic wall, a pair of anodes posie, tioned axially of said wall and having, juxtaposed, faces defining a space charge chamber within said envelope, each of said anodes having an ex-. ternally accessible conductive connection extending'through an end wall of said envelope and a cathode in operative relation to said anodes. a line resonator comprising substantially cylindrir, cal inner and outer concentric metallic 'conductors conductively connected to one end of said envelope, the outer conductor of said resonator being detachably connected to said wall and constituting a conductive extension thereof, the incomprising in combination an electron discharge device of the magnetron type including aniihera metically sealed envelope having asubstantially cylindrical metallic wall, a pair of anodes; posi-e, tioned axially of said wall and having juxtaposed faces defining, a space charge chamber within, saidfenvelope, each of said anodes havingan ex; ternally accessible conductive connection extend-.

ing through an insulating end wall of said-enve lope and a cathode in operative relation to said anodes, a line resonator comprising substantially cylindrical inner and outer concentric metallic conductors conductively connected, to, one end of said envelope, the, outer conductor of said resonator being detachably connected tosaid wall and-constituting: a conductive extension thereof,

swearin '15 the inner conductor of said resonator beingdetac'hably' connected to one 'ofsaid conductive-con ne'ctions and constituting a conductive extensic i'n thereof, tuning means within said resonator, means connected tosaid tuning means for adjustably positioning said tuning'means lon'git'udi nall'y' of'said resonator-whereby the frequency of oscillation of said generator may be varied, and means coupled to said generator for-energizing s'a-id g'e'nerator. a I

8.-=A'- generator of high" frequency oscillations com rising in combination-an electron -'discharge device of the magnetron type incl'uuiin'g an-hermetic'ally sealed-envelope having a substantially cylindrical metallic -wa 11, a pair ofanodes pOS1' i'ii'eined a Xia11y "of said wan and having juxtaposed faces efi n ing aspace charge chamberavithin' said nvelo'pe, eachof said a nodeshavin'g'a-n externally accessible conductive connection: -e'x-- tending throughanend' wall of said envelope and a' catho de in operative" relation to' said anodes; a pa n-of -1i-ne resonators each comprising subs-tanmany cylindrical inner and outer-concentric me-- tallic condiietors' ccnductively connected each'to one end-f said envelope, the outer conductor of "said resonator-being detachab-ly connectedto said" xv-2.1 1 afid 'constituti-ng aconductive e'xten si'on thereof, the innerconductor of each said resoa bi" being deta'chably connected each to onset said conductiveconnectionsand constitut mga-comuetivei extension-thereof, meanswit hin ea each of said "resonatorsat 'pred'eterinined points and means coupled-to said generator fer energiz mg saia-generate 19 enei 'ater" of-" 'hih frequency oscillations cofripr mg} in cenibinatien''-an electron discharge device 6f the magnetron ty e including an hermetically" 'se'a'led envelope having asubstantial iy cylifidrica-linieta-l-lic' Wall, a pair of anodespositionedaxiany of said wan and having juxtaposed faces defiriing a space charge chamber} within said efive16pe-, each of said-anodes having 'anex- Germany accessibleconductive connection eiz'tending: through: an end wall of said envelopeaiid" a" cath-bdein operative relation to -said anodes, a pairo f line resonators each comprising sii'b'stan'- tiai ly cylindrical inner and-outer concentric me tallie' eonduetor c-onduc'tively" connected each to Queen-a er said envele e, the outereonductor' of each said reson cor leeing detach'a'ifly connected tOSaidWafll' aiid constitutin a conductive ext'en's iorr thereof tkieii iner conductor of each said resonator-"being detach'abl-y conne'cted'jeach' t'o one- 'ofsald conductive connections andconstituting a cbndiicti-v e extension thereof} tuning eans Within each of saidiesonators; means connected to said tuning means for adjusta oiv positioning eachlof said tiining 'means iongitudinafly of said resonators w ekiy the" frequency of oscillation of saidgenei r' maygbvaried and means" ecupl'e'd fad-"said generator 'foi energizing" said' gen era'tor; v

14 2'0.- Aei1erator 6r tan-requests, oscillat ons (fifi lfilising' hi Cdmbinaifibn electrb'nidischarge devieecf t'iie- "magnetron typ'e"inc11idingan Herman-wily "sea-led envelope having a; substantially cylifidlicai "Wall, 3' I Ja'iY'Of afldds 113031-- tioned axially of said wail and having juxtaposed- Iaces defining-a space charge chamber with-in said envelope; eachof said'anodes having an ex tern'ally accessible condiictive c0nnection eXtend i'n'g' through'l anjefr'id' wan of said envelope, and-a;

' cathode inoperative "relation to said =anodes ;;a

said" resonator 'oonduct'ively terminating :13 pair of line resonators-{eaten comprising 'slibstanir'i'drical innerazid diiter concent m'eerifdil'ctors eeridiictively cemiected} acfito one end' 'of said' em/"e-l'olivei, the 'outercondue'tor of each of sem -resonate =-"-v:ieing detachablw'con- 1 nected tosai'd wall a d the rre'c uene ef oseiuatiom of Sa-id generator may be varied and means coupled to 'said generator for 'en'rg izing sain generator f V, 21; A: ene1=ator ef nigh i frequency osc'nrati V comr ing in cdmfloinati on 'n e-lectrcn dis f -the magfi'etro ype including-a h rmeti'caHys'eaIed env' lope" having a substantiany' tioneci a iall'yo'f -saidwal d haV i'I-ig junta d facesdefining a space charge chamber withinsaid envelope each of said-: anoaes nafvin an ex tawny-accessible condiiti ve mention: extendins-throng? an' ewane-ea dnve'iopaan a cathode in 'o'p atiVIBlaLtifio' -said: anodes a pair'ofinne resonators each c sin tially cylindrical inner -alfidoute cor-101 ic'Tnie-" tallic conductorsconauctiveiy connected: each to one end ofisaid-envelope, each of said-meson ors b titfltifig a cor idueti ve extension thereotwhe mner 'condnc V said"res'onatorsv be" g detachably' connected each to; one of" said no native 'eonnections arid certstitntin'g' a 'corid uctiv'ez extension there-dimming means withi rreach of saidiresenator 4 libstaifiial-ly equal iiiS- acercha ge chamber" ii/Her y the freqnencycfr scination rat be varied, means zwithifi for derivingiie'nergy therefrom," "mean connected t0sai'd last rfientioned means for ad tioning said last mentioned means nally of said "oneiof said resonator I a coupled to said-generator for energi'zmg said gen:- rator. i w

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